On Wed, 2008-05-14 at 14:25 -0700, Andrew Hammond wrote:
> I'd confirmation on how WAL files are named. I'm trying to write a
> tool which can tell me when we are missing a WAL file from the
> sequence. I initially thought that the file names were monotonically
> incrementing hexadecimal numbers. This doesn't appear to be the case.
>
> 00000001000001B7000000FD
> 00000001000001B7000000FE
> (there seem to be a whole bunch of missing filenames in the sequence
> here)
> 00000001000001B800000000
> 00000001000001B800000001
...
> Since I didn't specify a wal_segsize at compile time, it seems that my
> XLogSegsPerFile should be
> 0xffffffff / (16 * 1024 * 1024) = 255
> Which matches nicely with what I'm observing.
Yes, thats the default.
> So, and this is where I want the double-check, a tool which verifies
> there are no missing WAL files (based on names alone) in a series of
> WAL files needs to know the following.
>
> 1) Timeline history (although perhaps not, it could simply verify all
> existing timelines)
> 2) What, if any, wal_segsize was specified for the database which is
> generating the WAL files
Yes.
I wouldn't worry too much about the timeline id. Getting them sequential
within a single timeline is 99.998% of the problem.
> Am I missing anything? The format of .backup files seem pretty simple
> to me. So I intend to do the following.
> 1) find the most recent .backup file
> 2) verify that all the files required for that .backup exist
> 3) see if there are any newer files, and
> 4) if there are newer files, warn if any are missing from the sequence
>
> Would this be reasonable and is there any community interest in
> open-sourcing the tool that I'm building?
Sounds good.
-- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com
